Density functional theory study of interaction of graphene with hypoxanthine, xanthine, and uric acid

Abstract

Hypoxanthine (HX), xanthine (XA), and uric acid (UA) are important molecules in human beings. However, the physics underlying the interaction between these molecules and carbon nanomaterials is still unclear. In this study, we theoretically anlaysed the interaction of the graphene with HX, XA, and UA via the LDA, Perdew-Burke-Ernzerhof, and a second version of van der Waals (vdW)-DF2 exchange-correlation functionals of density functional theory. It was observed that these molecules could be adsorbed on the surface of the graphene steadily. The adsorption energies of these molecules on the graphene for the same site in vdW-DF2 functional show the following ordering: UA > XA > HX, the adsorption distances the following ordering: UA < XA < HX. The mechanism of this stable adsorption was revealed to be π -π and O-π interactions between these molecules and the graphene. Simulated scanning tunnelling microscopy (STM) images of HX, XA, and UA on the surface of the graphene layer as application, HX can be distinguished from XA and UA via the STM technique as a result of the interaction between the graphene and these molecules. The findings of this study provide a theoretical reference in the development and design of highly accurate biodevices and biosensors.

Covalent Functionalization of Graphene Oxide with a Presynthesized Metal–Organic Framework Enables a Highly Stable Electrochemical Sensing

“…The pH vs response current studies (Figure S14) show that two-electron/two-proton transfer processes are involved in the electrode reactions. These phenomena are in agreement with the density functional theory studies of the interaction of graphene with UA, XA, and HX, showing that there are π–π and O−π interactions between graphene and UA, XA, and HX molecules in electrochemical sensing …”

Elimination of Uremic Toxins by Functionalized Graphene-Based Composite Beads for Direct Hemoperfusion

“…These outcomes of free-energy profile were attributed as corresponding to the π−π interactions 50 and electrostatic and vdW interactions between uric acid and creatinine on the graphene surface. 69 The larger size of uric acid gave a broader and deep well of free energy, which can be clearly seen in Figure 5b. These interactions of uric acid and creatinine on GO had occurred on two surfaces: on the functionalized (hydroxyl or epoxy groups; Z = 4.5−4.8 Å) GO and on the native graphene surface (Z = ∼3 Å).…”

“…For the creatinine molecule in Figure c, the free-energy observed at ∼4.5 and ∼3.5 Å is −2.7 and −3.2 kcal mol –1 , respectively. These outcomes of free-energy profile were attributed as corresponding to the π–π interactions and electrostatic and vdW interactions between uric acid and creatinine on the graphene surface . The larger size of uric acid gave a broader and deep well of free energy, which can be clearly seen in Figure b.…”

“…The reason is not clear but may be because of the higher loading of CA in CAGO-17% that provides certain advantages. 69 Additionally, the incremental area under the curve (iAUC) for creatinine and uric acid during the adsorption is shown in Figure 4d,e, respectively. The higher adsorption performance of CAGO-22% (1617 mmol L −1 ) for creatinine and of CAGO-17% (1539 mmol L −1 ) for uric acid was in agreement with a significant difference (p < 0.005).…”

“…For uric acid in Figure c, we observed that the adsorption capacity of the CAGO-17% had a better performance than that of the CAGO-22% as the concertation was reduced with a significant difference ( p < 0.0001) from 93.4 to 73.07 μmol L –1 and to 54.14 μmol L –1 for CAGO-22% and CAGO-17%. The reason is not clear but may be because of the higher loading of CA in CAGO-17% that provides certain advantages . Additionally, the incremental area under the curve (iAUC) for creatinine and uric acid during the adsorption is shown in Figure d,e, respectively.…”